/*
 * Copyright (c) 2009-2012, Pieter Noordhuis <pcnoordhuis at gmail dot com>
 * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "../lib/intset.h"
#include "../lib/zmalloc.h"

/* Note that these encodings are ordered, so:
 * INTSET_ENC_INT16 < INTSET_ENC_INT32 < INTSET_ENC_INT64. */
#define INTSET_ENC_INT16 (sizeof(int16_t))
#define INTSET_ENC_INT32 (sizeof(int32_t))
#define INTSET_ENC_INT64 (sizeof(int64_t))

#define intrev32ifbe(v) (v)

/* Return the required encoding for the provided value. */
static uint8_t _intsetValueEncoding ( int64_t v )
{
    if ( v < INT32_MIN || v > INT32_MAX )
        return INTSET_ENC_INT64;
    else if ( v < INT16_MIN || v > INT16_MAX )
        return INTSET_ENC_INT32;
    else
        return INTSET_ENC_INT16;
}

/* Return the value at pos, given an encoding. */
static int64_t _intsetGetEncoded ( intset *is, int pos, uint8_t enc )
{
    int64_t v64;
    int32_t v32;
    int16_t v16;

    if ( enc == INTSET_ENC_INT64 )
    {
        memcpy (&v64, ( ( int64_t* ) is->contents ) + pos, sizeof (v64 ));
        return v64;
    }
    else if ( enc == INTSET_ENC_INT32 )
    {
        memcpy (&v32, ( ( int32_t* ) is->contents ) + pos, sizeof (v32 ));
        return v32;
    }
    else
    {
        memcpy (&v16, ( ( int16_t* ) is->contents ) + pos, sizeof (v16 ));
        return v16;
    }
}

/* Return the value at pos, using the configured encoding. */
static int64_t _intsetGet ( intset *is, int pos )
{
    return _intsetGetEncoded (is, pos, intrev32ifbe (is->encoding));
}

/* Set the value at pos, using the configured encoding. */
static void _intsetSet ( intset *is, int pos, int64_t value )
{
    uint32_t encoding = intrev32ifbe (is->encoding);

    if ( encoding == INTSET_ENC_INT64 )
    {
        ( ( int64_t* ) is->contents )[pos] = value;
    }
    else if ( encoding == INTSET_ENC_INT32 )
    {
        ( ( int32_t* ) is->contents )[pos] = value;
    }
    else
    {
        ( ( int16_t* ) is->contents )[pos] = value;
    }
}

/* Create an empty intset. */
intset *intsetNew ( void )
{
    intset *is = zmalloc (sizeof (intset ));
    is->encoding = intrev32ifbe (INTSET_ENC_INT16);
    is->length = 0;
    return is;
}

/* Resize the intset */
static intset *intsetResize ( intset *is, uint32_t len )
{
    uint32_t size = len * intrev32ifbe (is->encoding);
    is = zrealloc (is, sizeof (intset ) + size);
    return is;
}

/* Search for the position of "value". Return 1 when the value was found and
 * sets "pos" to the position of the value within the intset. Return 0 when
 * the value is not present in the intset and sets "pos" to the position
 * where "value" can be inserted. */
static uint8_t intsetSearch ( intset *is, int64_t value, uint32_t *pos )
{
    int min = 0, max = is->length - 1, mid = - 1;
    int64_t cur = - 1;

    /* The value can never be found when the set is empty */
    if ( is->length == 0 )
    {
        if ( pos ) *pos = 0;
        return 0;
    }
    else
    {
        /* Check for the case where we know we cannot find the value,
         * but do know the insert position. */
        if ( value > _intsetGet (is, is->length - 1) )
        {
            if ( pos ) *pos = intrev32ifbe (is->length);
            return 0;
        }
        else if ( value < _intsetGet (is, 0) )
        {
            if ( pos ) *pos = 0;
            return 0;
        }
    }

    while ( max >= min )
    {
        mid = ( ( unsigned int ) min + ( unsigned int ) max ) >> 1;
        cur = _intsetGet (is, mid);
        if ( value > cur )
        {
            min = mid + 1;
        }
        else if ( value < cur )
        {
            max = mid - 1;
        }
        else
        {
            break;
        }
    }

    if ( value == cur )
    {
        if ( pos ) *pos = mid;
        return 1;
    }
    else
    {
        if ( pos ) *pos = min;
        return 0;
    }
}

/* Upgrades the intset to a larger encoding and inserts the given integer. */
static intset *intsetUpgradeAndAdd ( intset *is, int64_t value )
{
    uint8_t curenc = intrev32ifbe (is->encoding);
    uint8_t newenc = _intsetValueEncoding (value);
    int length = intrev32ifbe (is->length);
    int prepend = value < 0 ? 1 : 0;

    /* First set new encoding and resize */
    is->encoding = intrev32ifbe (newenc);
    is = intsetResize (is, intrev32ifbe (is->length) + 1);

    /* Upgrade back-to-front so we don't overwrite values.
     * Note that the "prepend" variable is used to make sure we have an empty
     * space at either the beginning or the end of the intset. */
    while ( length -- )
        _intsetSet (is, length + prepend, _intsetGetEncoded (is, length, curenc));

    /* Set the value at the beginning or the end. */
    if ( prepend )
        _intsetSet (is, 0, value);
    else
        _intsetSet (is, intrev32ifbe (is->length), value);
    is->length = intrev32ifbe (intrev32ifbe (is->length) + 1);
    return is;
}

static void intsetMoveTail ( intset *is, uint32_t from, uint32_t to )
{
    void *src, *dst;
    uint32_t bytes = intrev32ifbe (is->length) - from;
    uint32_t encoding = intrev32ifbe (is->encoding);

    if ( encoding == INTSET_ENC_INT64 )
    {
        src = ( int64_t* ) is->contents + from;
        dst = ( int64_t* ) is->contents + to;
        bytes *= sizeof (int64_t );
    }
    else if ( encoding == INTSET_ENC_INT32 )
    {
        src = ( int32_t* ) is->contents + from;
        dst = ( int32_t* ) is->contents + to;
        bytes *= sizeof (int32_t );
    }
    else
    {
        src = ( int16_t* ) is->contents + from;
        dst = ( int16_t* ) is->contents + to;
        bytes *= sizeof (int16_t );
    }
    memmove (dst, src, bytes);
}

/* Insert an integer in the intset */
intset *intsetAdd ( intset *is, int64_t value, uint8_t *success )
{
    uint8_t valenc = _intsetValueEncoding (value);
    uint32_t pos;
    if ( success ) *success = 1;

    /* Upgrade encoding if necessary. If we need to upgrade, we know that
     * this value should be either appended (if > 0) or prepended (if < 0),
     * because it lies outside the range of existing values. */
    if ( valenc > intrev32ifbe (is->encoding) )
    {
        /* This always succeeds, so we don't need to curry *success. */
        return intsetUpgradeAndAdd (is, value);
    }
    else
    {
        /* Abort if the value is already present in the set.
         * This call will populate "pos" with the right position to insert
         * the value when it cannot be found. */
        if ( intsetSearch (is, value, &pos) )
        {
            if ( success ) *success = 0;
            return is;
        }

        is = intsetResize (is, intrev32ifbe (is->length) + 1);
        if ( pos < intrev32ifbe (is->length) ) intsetMoveTail (is, pos, pos + 1);
    }

    _intsetSet (is, pos, value);
    is->length = intrev32ifbe (intrev32ifbe (is->length) + 1);
    return is;
}

/* Delete integer from intset */
intset *intsetRemove ( intset *is, int64_t value, int *success )
{
    uint8_t valenc = _intsetValueEncoding (value);
    uint32_t pos;
    if ( success ) *success = 0;

    if ( valenc <= intrev32ifbe (is->encoding) && intsetSearch (is, value, &pos) )
    {
        uint32_t len = intrev32ifbe (is->length);

        /* We know we can delete */
        if ( success ) *success = 1;

        /* Overwrite value with tail and update length */
        if ( pos < ( len - 1 ) ) intsetMoveTail (is, pos + 1, pos);
        is = intsetResize (is, len - 1);
        is->length = intrev32ifbe (len - 1);
    }
    return is;
}

/* Determine whether a value belongs to this set */
uint8_t intsetFind ( intset *is, int64_t value )
{
    uint8_t valenc = _intsetValueEncoding (value);
    return valenc <= intrev32ifbe (is->encoding) && intsetSearch (is, value, NULL);
}

/* Return random member */
int64_t intsetRandom ( intset *is )
{
    return _intsetGet (is, rand () % intrev32ifbe (is->length));
}

/* Sets the value to the value at the given position. When this position is
 * out of range the function returns 0, when in range it returns 1. */
uint8_t intsetGet ( intset *is, uint32_t pos, int64_t *value )
{
    if ( pos < intrev32ifbe (is->length) )
    {
        *value = _intsetGet (is, pos);
        return 1;
    }
    return 0;
}

/* Return intset length */
uint32_t intsetLen ( intset *is )
{
    return intrev32ifbe (is->length);
}

/* Return intset blob size in bytes. */
size_t intsetBlobLen ( intset *is )
{
    return sizeof (intset ) + intrev32ifbe (is->length) * intrev32ifbe (is->encoding);
}

#ifdef REDIS_TEST
#include <sys/time.h>
#include <time.h>

#if 0

static void intsetRepr ( intset *is )
{
    for ( uint32_t i = 0; i < intrev32ifbe (is->length); i ++ )
    {
        printf ("%lld\n", ( uint64_t ) _intsetGet (is, i));
    }
    printf ("\n");
}

static void error ( char *err )
{
    printf ("%s\n", err);
    exit (1);
}
#endif

static void ok ( void )
{
    printf ("OK\n");
}

static long long usec ( void )
{
    struct timeval tv;
    gettimeofday (&tv, NULL);
    return (( ( long long ) tv.tv_sec )*1000000 )+ tv.tv_usec;
}

#define assert(_e) ((_e)?(void)0:(_assert(#_e,__FILE__,__LINE__),exit(1)))

static void _assert ( char *estr, char *file, int line )
{
    printf ("\n\n=== ASSERTION FAILED ===\n");
    printf ("==> %s:%d '%s' is not true\n", file, line, estr);
}

static intset *createSet ( int bits, int size )
{
    uint64_t mask = ( 1 << bits ) - 1;
    uint64_t value;
    intset *is = intsetNew ();

    for ( int i = 0; i < size; i ++ )
    {
        if ( bits > 32 )
        {
            value = ( rand () * rand () ) & mask;
        }
        else
        {
            value = rand () & mask;
        }
        is = intsetAdd (is, value, NULL);
    }
    return is;
}

static void checkConsistency ( intset *is )
{
    for ( uint32_t i = 0; i < ( intrev32ifbe (is->length) - 1 ); i ++ )
    {
        uint32_t encoding = intrev32ifbe (is->encoding);

        if ( encoding == INTSET_ENC_INT16 )
        {
            int16_t *i16 = ( int16_t* ) is->contents;
            assert (i16[i] < i16[i + 1]);
        }
        else if ( encoding == INTSET_ENC_INT32 )
        {
            int32_t *i32 = ( int32_t* ) is->contents;
            assert (i32[i] < i32[i + 1]);
        }
        else
        {
            int64_t *i64 = ( int64_t* ) is->contents;
            assert (i64[i] < i64[i + 1]);
        }
    }
}

#define UNUSED(x) (void)(x)

int intsetTest ( int argc, char **argv )
{
    uint8_t success;
    int i;
    intset *is;
    srand (time (NULL));

    UNUSED (argc);
    UNUSED (argv);

    printf ("Value encodings: ");
    {
        assert (_intsetValueEncoding (- 32768) == INTSET_ENC_INT16);
        assert (_intsetValueEncoding (+ 32767) == INTSET_ENC_INT16);
        assert (_intsetValueEncoding (- 32769) == INTSET_ENC_INT32);
        assert (_intsetValueEncoding (+ 32768) == INTSET_ENC_INT32);
        assert (_intsetValueEncoding (- 2147483648) == INTSET_ENC_INT32);
        assert (_intsetValueEncoding (+ 2147483647) == INTSET_ENC_INT32);
        assert (_intsetValueEncoding (- 2147483649) == INTSET_ENC_INT64);
        assert (_intsetValueEncoding (+ 2147483648) == INTSET_ENC_INT64);
        assert (_intsetValueEncoding (- 9223372036854775808ull) ==
                INTSET_ENC_INT64);
        assert (_intsetValueEncoding (+ 9223372036854775807ull) ==
                INTSET_ENC_INT64);
        ok ();
    }

    printf ("Basic adding: ");
    {
        is = intsetNew ();
        is = intsetAdd (is, 5, &success);
        assert (success);
        is = intsetAdd (is, 6, &success);
        assert (success);
        is = intsetAdd (is, 4, &success);
        assert (success);
        is = intsetAdd (is, 4, &success);
        assert (! success);
        ok ();
    }

    printf ("Large number of random adds: ");
    {
        uint32_t inserts = 0;
        is = intsetNew ();
        for ( i = 0; i < 1024; i ++ )
        {
            is = intsetAdd (is, rand () % 0x800, &success);
            if ( success ) inserts ++;
        }
        assert (intrev32ifbe (is->length) == inserts);
        checkConsistency (is);
        ok ();
    }

    printf ("Upgrade from int16 to int32: ");
    {
        is = intsetNew ();
        is = intsetAdd (is, 32, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT16);
        is = intsetAdd (is, 65535, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT32);
        assert (intsetFind (is, 32));
        assert (intsetFind (is, 65535));
        checkConsistency (is);

        is = intsetNew ();
        is = intsetAdd (is, 32, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT16);
        is = intsetAdd (is, - 65535, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT32);
        assert (intsetFind (is, 32));
        assert (intsetFind (is, - 65535));
        checkConsistency (is);
        ok ();
    }

    printf ("Upgrade from int16 to int64: ");
    {
        is = intsetNew ();
        is = intsetAdd (is, 32, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT16);
        is = intsetAdd (is, 4294967295, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT64);
        assert (intsetFind (is, 32));
        assert (intsetFind (is, 4294967295));
        checkConsistency (is);

        is = intsetNew ();
        is = intsetAdd (is, 32, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT16);
        is = intsetAdd (is, - 4294967295, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT64);
        assert (intsetFind (is, 32));
        assert (intsetFind (is, - 4294967295));
        checkConsistency (is);
        ok ();
    }

    printf ("Upgrade from int32 to int64: ");
    {
        is = intsetNew ();
        is = intsetAdd (is, 65535, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT32);
        is = intsetAdd (is, 4294967295, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT64);
        assert (intsetFind (is, 65535));
        assert (intsetFind (is, 4294967295));
        checkConsistency (is);

        is = intsetNew ();
        is = intsetAdd (is, 65535, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT32);
        is = intsetAdd (is, - 4294967295, NULL);
        assert (intrev32ifbe (is->encoding) == INTSET_ENC_INT64);
        assert (intsetFind (is, 65535));
        assert (intsetFind (is, - 4294967295));
        checkConsistency (is);
        ok ();
    }

    printf ("Stress lookups: ");
    {
        long num = 100000, size = 10000;
        int i, bits = 20;
        long long start;
        is = createSet (bits, size);
        checkConsistency (is);

        start = usec ();
        for ( i = 0; i < num; i ++ ) intsetSearch (is, rand () % ( ( 1 << bits ) - 1 ), NULL);
        printf ("%ld lookups, %ld element set, %lldusec\n",
                num, size, usec () - start);
    }

    printf ("Stress add+delete: ");
    {
        int i, v1, v2;
        is = intsetNew ();
        for ( i = 0; i < 0xffff; i ++ )
        {
            v1 = rand () % 0xfff;
            is = intsetAdd (is, v1, NULL);
            assert (intsetFind (is, v1));

            v2 = rand () % 0xfff;
            is = intsetRemove (is, v2, NULL);
            assert (! intsetFind (is, v2));
        }
        checkConsistency (is);
        ok ();
    }

    return 0;
}
#endif
